The present invention describes a family of new and unique pyrotechnic compositions and a method of preparing them. The compositions consist of selected metallic and nonmetallic salts of decahydrodecaboric acid, in combination with certain oxidizing agents. The method of preparing the compositions results in chemical substances in which there is intercrystalline mixing of the substituents, in a chemical state not obtainable by physical blending.
The unique character of the new compositions is produced by the method of manufacture. In the process, the decahydrodecaborate (-2) salt and oxidizer are dissolved in a suitable solvent. The solution containing the salt and oxidizer are pumped under pressure through a nozzle into a mixing chamber containing a high flow rate of a suitable nonsolvent. The dissolved ingredients are rapidly precipitated into very fine intertwined crystals containing the original constituents in a different physical and chemical environment than the starting crystals.
The physical, thermochemical, and kinetic properties of the new compositions are radically different than the corresponding physical blends of the starting ingredients. The pyrotechnic performance of the new compositions is wholly unpredicted by studies of the corresponding physical blends. Analysis of the infrared spectra of the subject compositions reveals that the critical ingredients, in particular the decahydrodecaborate (-2) ion, are in different chemical environments than the starting ingredients. In addition, the particles produced by the rapid precipitation are of smaller and more uniform particle size than the starting ingredients. These facts demonstrate that the decahydrodecaborate (-2) ion is in very intimate contact with the oxidizing species, which results in far more uniform and predictable burning than is obtainable by other means of combining the ingredients.
The compositions of this invention are very useful for a variety of purposes. They are excellent ignition materials for other pyrotechnic, incendiary, or propellant compositions, such as gun and rocket propellants. Confined in a metal sheath, they exhibit a range of burn rates and stability unobtainable by any other compositions. They can be incorporated as burn rate catalysts into rocket and gun propellants. A rocket or gun propellant can be made from the subject compositions by combining them with a suitable binder and other pyrotechnic ingredients and stabilizers; the propellants made by this method exhibit a fast burn rate wholly unobtainable by using physical blends of oxidizers and fuels in a similar binder.
The most significant property of the final compositions is that, despite a very high energy content, they do not detonate when confined, but burn at a steady and predictable rate.